Zeppelin propeller - or maybe not..

[Marijnvanderuit]

Dear fellow aviation enthusiasts,

Let me first apologize for placing a first post in this forum, which again is yet another desperate cry for help about a propeller identification. Things are as such:

I am very much interested in Naval Zeppelins, which were of course equipped with Lorenzen, Garuda and Jaray propellers. Some time ago I ran into a dealer of old aircraft parts, who also sells a propeller which supposedly belonged to the L33, An R-type Zeppelin which was downed in 1916.

General details of the airship say that it was equipped with 6 Maybach engines and 6 Lorenzen props, all between 5000 an 5800 mm diameter.

The prop that I am interested in is only partially complete, it represents a single blade with the prop hub. The hub has been widened, to allow the mounting of a clock. The tip of the blade is missing aswell. The prop itself has been surface treated/sanded down around the hub, to give it a 'nicer' appearance (such a shame).

Imprints on the prop are:

ETA (imprint on the forward face of the prop).

4560. EDULZUG (so it's a tractor, whilst the zepp only has pushers?)

ST 265/30. (so the pitch is rather high)

310 ( with a theta symbol in front of it. Mind you the 3 in front of the 1 and the 0 is questionable and could be a 5 aswell)

So what we can see is that according to the markings, it was produced by ETA Luftschraubenwerke, and it had a diameter of just over 3 meter. Now I would immediately say that this is not a prop from the L33, but I am not an expert on this field!

I noticed for example that the Imperial War Museum has a prop from L33, which has a diameter of only 2740 mm (exhibit AIR 416), which doesn't match with my knowledge of L33's propulsion. Also, they specify two ETA propellers ( AIR 406 and AIR 403) as Zeppelin propellers, allthough to my knowledge Zeppelins never used ETA props?

As you can see, I am completely lost, I don't want to spend money on something which is not what I think it is, but I also don't want to let it go allthough it might actually be authentic. Any help would be appreciated!

Best regards from the Netherlands,

Marijn

[Dbahnson]

Hopefully Bob Gardner, who has already completed several books on German propellers, will chime in but it sounds as if you've done your homework and are on the right track, wherever it leads.

I'm always suspicious of seller's claims that can't be readily verified, as even the seller often believes the claim to be true and simply passes it on.

[Marijnvanderuit]

You're right, and this isn't the first time that I run into a Zeppelin propeller, which doesn't appear to be what it is sold for. In this case though, the seller was honest enough to mention that he can't verify the props true origin.

A small silver plaquet has been attached to the prop blade, which reads "L33, 1916". That was the clue that the seller used to determine the props origin.

I'm very eager to learn what these props were used for, it is an intriguing piece.

Kind regards,

Marijn

[Bob Gardner]

Marijn,

Don't buy it.

(It took me many years to realize that retreating from a purchase with my money intact was always a success. It's intact for the next opportunity.)

I have been researching German WW1 propellers for a quarter of a century and have not yet seen a Zeppelin propeller, although I have seen perhaps thirty which were advertised as Zeppelin props!

I know of eleven ETA props of which eight were for engines between 200 and 260ps. Three have dimensions which are similar to yours. I should add that Paul Borrmann who owned Eta must have had an education in the classics, particularly Greek, because the name Eta is the fifth letter of the Greek alphabet and the mathematical symbol for propeller efficiency. The symbol Theta was similarly the symbol in German mathematics for diameter.

The three props most similar to yours have a diameter of 3100mm and a pitch (Steigung) of 2050/30. Perhaps your figure of 265cm is really 205 cm? I don't know what /30 means; possibly 30cms for blade width. All three were used with the Maybach 260ps engine and my notes suggest they were used on a Rumpler, although why I once came to this conclusion I now don't know.

Eta was formed in 1910 and probably was a general dealer in aviation items. An undated memo lists them as making propellers, ventilation equipment, aircraft parts, car parts, photographic equipment and explosive projectiles. A 1916 cutting appears to suggest that they were now only prop makers.

The navy airship L33 was shot down in September 1916. The props were 5300mm and 4700mm in diameter. The crew set their downed ship on fire and the propellers were mostly burned to destruction, but some remnants were recovered and the seven laminations were of mahogany in conventional horizontal format. Eta was unique in using vertical laminations.

So circumstantial evidence makes it unlikely that Eta was making any propellers when L33 was built and the construction of the burnt L33 props is conventional, whereas ETA's was atypical. Also, all airship props had copper wire along their edges as earths for static electricity. QED.

So, don't buy it!

With kind regards and met vriendelijke groet,

Bob

[Marijnvanderuit]

Hey Bob,

Thank's véry much for the prompt answer and explanation. I guess it was just to good to be true (which was my first clue that something was foul).

I noticed in my documentation that the starboard outboard propeller survived nearly intact from the L33 crash. Also, the starboard prop on the mid-ship gondola survived partially, loosing only one blade. Do you know where these props went?

It is interesting that you mentioned that ETA used vertical laminations, which is quite clearly visible at the hub, on the propeller that this topic relates to. Do you know why they went down this route / followed this alternative technique?

PS. The good thing about all this is that I know definately have to get your books on german prop manufacturers..

Best regards, en vriendelijke groeten terug,

Marijn

[Bob Gardner]

Dank u Marijn,

I see you live in Culemborg. I have passed though Utrecht about a thousand times, when I was stationed with the British Army on the Dutch-German border, when I used to attend NATO conferences in den Haag, and latterly coming to Lelystadt for the bird watching and visiting Dutch and German museums to research German WW1 props.

The remnants of L33's props were recovered by the British who analysed them in detail. I don't know where they are now. Possibly thrown away after the analysis. I can send you a copy of the intelligence report if you like. Email me aeroclocksatbtinternetdotcom, written thus to avoid the spam bots.

I can also send you a pdf of my research into Eta if you wish. The reason you can see the vertical laminations at the hub is that Eta laminated their prop blades with birch; another strange variation.

I have recorded all the German props owned by the IWM but none were attributed to an airship. I'll have a look at your air documents.

I think you'll enjoy my German books. The first describes the German prop industry, then Part One and Two describe makers from Adastra to Garuda (Pt One 200 pages 292 photos) and Geest to LZ in Pt Two, 180 pages 234 photos.

If you buy two or three there are savings in packing and postage and I'll give you some discount. If this idea appeals, email me rather than buying them through my website and I'll work out a price for you (but I'm out of office for a few days so don't expect an immediate reply.)

Tschüß, to revert to Deutsch,

Bob

[Marijnvanderuit]

Hey Bob,

Correct, I actually moved their only three weeks ago, since I have worked in the area for the last few year, but till now I used to cross half the country to get their every morning. If you came to Lelystadt very often, are you familiar with the 'Stichting Vroege Vogels'? They restore world war I type airplanes, and I visited them (for business) just two months ago. I don't think I have ever seen so much wooden props stuffed into two hangars, I really enjoyed the visit anyway.

I send you an email concerning the L33 report, you research on the ETA props (I'm very interested in that), and some of the books I'd like to order.

Thanks again for the help, and I am looking forward to your opinion on the AIR documents.

Cheers, und mit freundlichem Gruss,

Marijn

[Bob Gardner]

Correction

Having gone back to my base documents I find that my memory is awry. Eta did make props for L33 and apparently other airships. But the diameters in L33 were 5300mm, about seventeen feet, not the 3100mm in the Eta prop Marijn was offered.

Bob